JP2956397B2 - High pressure generator for electric precipitator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage generator which oscillates high-frequency waves by an oscillating circuit, boosts and rectifies the oscillated high-frequency waves, obtains a high voltage, and supplies it to a dust-collecting element of an electric precipitator. .

[0002]

2. Description of the Related Art An electrostatic precipitator used in an air purifier or the like is a type of dust collector in which inhaled air is passed through an ionizing section to perform corona discharge, and air that has passed through the ionizing section is subjected to high voltage dust collection. The structure is such that charged dust in the air is guided between the elements and adheres to the dust collecting element.

FIG. 4 is a circuit diagram of a conventional high voltage generator for supplying a high voltage to the dust collecting element 5. In the circuit of the high-pressure generating device is inserted oscillation transistor Q ₁ to the transformer primary winding T _1, the tertiary winding T ₃ of the transformer, the current I flowing through the dust collecting element 5 overcurrent protection circuit 3 is connected with the increased lowering the high voltages V ₁ functions. The oscillation transistor Q ₁
The base, which drive current is supplied through the resistor R _1, whereby the oscillation transistor Q ₁ is made to be subjected to activation. The transformer secondary winding T ₂ Yes with boost rectifier circuit 4 is provided, high DC voltages V ₁ is the output of which is supplied to the dust collecting element 5 through a resistor R _2.

[0004] Figure 5 is a voltage waveform diagram of each part, and the power is turned on at some point t = 0 (see FIG. 5 (a)), the base of the oscillation transistor Q ₁ is a power supply through a resistor R ₁ connection, the transistor Q ₁ is initiating the pulse operation (see FIG. 5 (b) .V _bE denotes the base-emitter voltage).
As a result, the output voltage V ₁ of the step-up rectifier circuit 4 increases to the rated value (see FIG. 5C), and the voltage HV of the dust collecting element 5 via the resistor R ₂ also gradually increases to the rated value (see FIG. 5C). 5 (d
1)). The reason why the rise of the voltage HV is gradual is that the capacity C ₁ and C ₂ of the dust collecting element 5 and the capacity C ₃ of the high pressure generator (see FIG. 4) are charged. Therefore, a high voltage can be applied to the dust collection element 5.

In such an electric dust collector, if a large amount of dust accumulates on the dust collecting element, an arc discharge may occur between the dust collecting element and the dust or between the dusts. The collected dust includes non-flammable substances such as dust, as well as combustible substances such as tobacco tar and carbon. There is a possibility that.

Therefore, it is necessary to detect the occurrence of the arc discharge as soon as possible and take measures to prevent ignition. Conventionally,
In order to detect the occurrence of arc discharge, a signal corresponding to this is output as a cutoff signal by detecting whether the time width during which the voltage supplied to the dust collecting element falls below a certain voltage is longer than a reference time. A method has been adopted (see JP-A-62-168559).

[0007]

In the above detection method,
For a few seconds immediately after turning on the high-voltage generator,
Detection is prohibited and high-voltage output is forcibly generated. This
Is due to the capacitance C of the dust collection element.₁, C_TwoAnd high
Pressure generator capacity C _ThreePower supply of the high voltage generator
Immediately after the dust collection, as shown in Fig. 5 (d1),
Since it takes some time for the pressure HV to rise,
The voltage is still rising when technologies like the gazette are adopted.
Arc discharge even immediately after turning on the high-voltage generator
Will be mistakenly detected as having occurred and the power will be turned off.
It is.

[0008] For this reason, a problem occurs particularly when the arc discharge occurs in the dust-collecting element during the boosting for several seconds immediately after the power is turned on, that is, during the arc discharge detection prohibition period (shown as τ _{1 in} FIG. 5). Occurs. Referring again to the circuit of FIG. 4, if an arc discharge occurs in the dust collecting element 5 during boosting, a large current flows through the dust collecting element 5 at that point, and the voltage HV drops sharply. Overcurrent protection circuit 3 reduces the output voltages V ₁ detects this.
For this reason, although the voltage HV of the dust collecting element 5 also decreases,
Since the oscillation transistor Q ₁ is multiplied by the constant start-up,
It returns to the on state again, and raises voltage HV.

Therefore, depending on the degree of adhesion of dust, arc discharge may continue intermittently (FIG. 5 (d2)).
reference). For this reason, abnormal noise may be continued, giving a feeling of discomfort to a person, and may be ignited due to continued arc discharge. Therefore, an object of the present invention is to solve the above-described technical problem, and even if an arc discharge occurs in the dust collection element 5 during the pressure increase immediately after the power is turned on, this is reliably detected and the arc discharge is stopped. It is an object of the present invention to provide a high-pressure generator which can be operated.

[0010]

According to a first aspect of the present invention, there is provided a high-voltage generating apparatus for activating an oscillation circuit for activating the oscillation circuit after power is turned on, as shown in FIG. A circuit 1 and an overcurrent protection circuit 3 for temporarily stopping the oscillation function of the oscillation circuit 2 when the overcurrent is detected, thereby lowering the output voltage of the oscillation high-voltage generating device. The oscillation circuit 2 is activated by generating a single trigger signal after the rise, and the oscillation circuit 2 continues self-excited oscillation after the activation.

The high-voltage generating device according to the second aspect of the present invention includes an arc discharge detecting circuit for detecting an arc discharge generated in the dust collecting element 5 and an arc discharge by the arc discharge detecting circuit for a certain period after power-on. And a detection prohibition circuit for prohibiting the detection of.

[0012]

According to the above configuration, when the oscillation start circuit 1 is started by the oscillation start circuit 1 after the power is turned on, a high frequency is oscillated, boosted and rectified to a high voltage, and the high frequency is applied to the dust collection element 5 of the electric precipitator. Supplied. If the dust collection element 5
When an overcurrent flowing through the dust collecting element 5 is detected due to the occurrence of an arc discharge in the dust collector 5, the oscillation function of the oscillation circuit 2 is temporarily stopped by the overcurrent protection circuit 3. Since the self-sustained pulsation only continues, if the oscillating function is temporarily stopped, the oscillating function cannot be resumed thereafter.

Therefore, the occurrence of arc discharge is suppressed to one time, and no subsequent continuous discharge occurs.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 2 is a circuit diagram showing one embodiment of the present invention. In the circuit of the high-pressure generating device is inserted oscillation transistor Q ₁ to the transformer primary winding T _1, the tertiary winding T ₃ of the transformer, the current I flowing through the dust collecting element 5 overcurrent protection circuit 3 is connected with the increased lowering the high voltages V ₁ functions. Transformer 2
The following side winding T ₂ 2 double boosting rectifier circuit 4 Yes is provided, high DC voltages V ₁ is the output of which is supplied to the dust collecting element 5 through a resistor R _2.

[0015] The above configuration is similar to the conventional circuit shown in FIG. 4, the base of the oscillation transistor Q ₁ is, connected to the oscillator starting circuit 1 through a resistor R ₁ and the oscillation start transistor Q ₂ However, there is a difference from the conventional circuit. The oscillation starting circuit 1 is a circuit that generates a single-shot trigger signal having a time width τ ₂ after a predetermined time from power-on,
The circuit configuration itself is known (for example, it can be configured using an operational amplifier or the like).

[0016] As a result of the oscillation transistor Q ₁ is multiplied by the start-up is only when the oscillation start transistor Q ₂ is turned on. FIG. 3 is a voltage waveform diagram of each part. When the power is turned on at a certain time t = 0 (FIG. 3 (a)
See), supplies a voltage to the base of the oscillation start transistor Q ₂ oscillation starting circuit 1 in conjunction therewith reference (Figure 3 (b)). The duration τ ₂ of the single trigger signal, which is the voltage supply time, is equal to the base-emitter voltage of the transistor Q ₁ being 2
It is set to be almost equal to the time (about 30 .mu.sec) of changing by the pulse. When the base voltage to the oscillation start transistor Q ₂ is supplied the base of the transistor Q ₁ is the power supply and the connection through the resistor R _1, the transistor Q ₁ is initiating the pulse operation (see Figure 3 (c)). Although the two pulses operation persists oscillation startup transistor Q ₂ turns off, the output voltage V ₁ of the booster rectifier circuit 4 increases to approximately the rated value at this time (see FIG. 3 (d)), the resistance R ₂ The voltage HV of the dust-collecting element 5 via the filter also gradually increases to the rated value (FIG. 3 (e)
1)).

If an arc discharge occurs in the dust collecting element 5 in this state, a large current flows through the dust collecting element 5 at that point, and the voltage HV drops rapidly. Overcurrent protection circuit 3
Detects this, reduces the output voltage V _1, and therefore the voltage HV of the dust collecting element 5 also decreases. In this case, the oscillation transistor Q ₁ is because only are self-oscillation does not return to the state once turned off, the voltage HV disappears (see FIG. 3 (e2)).

For this reason, the arc discharge ends in a single shot,
Almost no discomfort due to abnormal noise can be eliminated, which can contribute to improvement of safety.

[0019]

As described above, according to the high voltage generator of the present invention, when an arc discharge occurs in the dust collecting element and an overcurrent flowing through the dust collecting element is detected, the oscillation circuit Stops the oscillation and cannot resume the oscillation thereafter. Therefore, subsequent continuous discharge does not occur, safety is improved, and no discomfort due to abnormal noise or the like is felt.

In a preferred embodiment of the present invention, the apparatus further comprises an arc discharge detection circuit and a detection prohibition circuit. During the period in which the detection of the original arc discharge is prohibited after the power is turned on, the arc is discharged to the dust collecting element. Occurs, there is no other means for detecting this, so the configuration of the present invention is particularly effective.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a high-pressure generator.

FIG. 2 is a circuit diagram showing one embodiment of a high-pressure generator.

FIG. 3 is a voltage waveform diagram of each part in the circuit of FIG. 2;

FIG. 4 is a circuit diagram of a conventional high voltage generator for supplying a high voltage to a dust collecting element.

5 is a voltage waveform diagram of each part in the circuit of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oscillation starting circuit 2 Oscillation circuit 3 Overcurrent protection circuit 4 Boost rectifier circuit 5 Dust collection element

Claims (2)

(57) [Claims] A high frequency is oscillated by an oscillation circuit (2).
A high-voltage generator for boosting and rectifying the oscillated high frequency to obtain a high voltage and supplying it to a dust-collecting element (5) of an electrostatic precipitator, for starting the oscillating circuit (2) after power-on. An oscillation start circuit (1); and an overcurrent protection circuit (3) that, when an overcurrent is detected, temporarily stops the oscillation function of the oscillation circuit (2) to reduce the output voltage of the high-voltage generator. The activation circuit (1) activates the oscillation circuit (2) by generating a single trigger signal after power-on, and the oscillation circuit (2) continues self-oscillation after activation. A high pressure generator for an electrostatic precipitator. 2. An arc discharge detection circuit for detecting an arc discharge generated in a dust collecting element, and a detection prohibition circuit for prohibiting the arc discharge detection circuit from detecting the arc discharge for a certain period after power-on. The high-pressure generator for an electrostatic precipitator according to claim 1, further comprising: